The present invention relates to an exhaust system and a mini-exhaust static pressure controlling apparatus thereof.
In a semiconductor foundry, it is important to keep the environmental conditions under control. Airborne molecular contaminations (AMCs) such as articles and other floating dirt can be harmful to the environmental conditions and should be maintained under a preferred level.
Generally, the AMCs can be categorized to two types, i.e. the environmental contamination and the tool contamination. Conventionally, a filtration system, such as an exhaust system, can be applied in the foundry to reduce the tool contamination. The conventional exhaust system provides capability to draw out pollution from the tools.
An example of the conventional exhaust system is described with respect to FIG. 1. In FIG. 1, a process area 50 is provided with tools and machines disposed therein. In the process area 50, a plurality of fans 52 can be disposed at the inlets thereof, and a mass flow control valve 110 is provided at the outlet thereof. The mass flow control valve 110 can be formed with a throttle, a vacuum diffuser, or a piston. The air inlet of the mass flow control valve 110 is ducted to the process area 50, in which the tools and machines are disposed, for reducing tool contamination. The pressure in the mass flow control valve 110 can be set under room air pressure by the piston, and the throttle and the vacuum diffuser turn on and off such that the piston floats, ensuring a closed-type space for the mass flow control valve 110. Further, pressure in the valve 110 can be increased so that the high-pressure setting improves exhaust outward performance and capability of the exhaust system.
In the conventional exhaust system, however, the mass flow control valve 110 is a closed-type valve with all elements sealed inside the valve. Accordingly, adjustment of the elements is predetermined and difficult to refine, and maintenance for the valve is difficult. Further, the high-pressure setting of the mass flow control valve 110 has an impact to operation of the tools and machines in the process area 50, which might be hazardous in the long-term manufacture.
Conventionally, a chemical filter can be employed in the exhaust system to reduce the tool contamination and improve the performance thereof. In this case, however, cost of the exhaust system is increased.